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Re: Transition functions for SUM(::int2), SUM(::int4, SUM(::int8]) - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Transition functions for SUM(::int2), SUM(::int4, SUM(::int8])
Date
Msg-id 25794.1201640819@sss.pgh.pa.us
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In response to Transition functions for SUM(::int2), SUM(::int4, SUM(::int8])  (Caleb Welton <cwelton@greenplum.com>)
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Caleb Welton <cwelton@greenplum.com> writes:
> Forgive me if I'm being dense, but could you explain why

> int4_sum(bigint,int) must not be strict, but
> int4_avg_accum(bytea, int) can be strict?

The former is used with a NULL initial value, the latter isn't.
Read the fine print in the CREATE AGGREGATE man page about behavior
with strict transition functions.
        regards, tom lane

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